The use of plastic wheels on a variety of products has dramatically increased in recent years. One area where such plastic wheels have been widely employed is on wheeled refuse or garbage carts or bins of the type commonly employed by homeowners for their trash. Typically, these carts are formed of an injection, blow or rotationally molded plastic and have injection, blow, rotation or compression molded plastic wheels which are mounted on the ends of a metal axle by a hub member or push-on hat fastener (sometimes referred to as “pawl nut”). The wheel hub is hammered onto the end of the axle to hold the wheel in place. Removal of such plastic wheels in order to replace or repair the wheel or the cart has been difficult because the hammered push-on hat fasteners or hubs require special tools for their removal or essentially must be destroyed to remove them from the axle. Sometimes this process also damages the axles. Thus, more recently, wheel-mounting sleeve assemblies have been devised which snap-on to the axle to hold the wheel to the axle.
As the size of the axle and wheel are reduced, for example, when such wheel assemblies are used on wheeled toys, wagons, coolers or the like, the amount of material which can be employed in a wheel mounting sleeve to stabilize the coupling of the axle to the wheel decreases. Since such mounting sleeves often employ resiliently transversely displaceable fingers to lock or latch the wheel to the axle, the area of the sleeve which includes the displaceable finger tends to be somewhat less stable and less capable of supporting shifting or rocking along the axle and transverse loads on the axle. The stability decreases as the sleeve size decreases and there is less material to engage and hold onto, or latch to, the axle and to resist axial shifting and transverse loading in the area of the resiliently transversely displaceable fingers, which usually are located proximate an outer end of the axle.
Prior art snap-on wheel-mounting assemblies have been unduly complex, visually unappealing, and not well suited to the shock loading and vibration which is commonly encountered. They also are not easily adaptable for use on smaller axles and smaller wheeled products. Moreover, the cost of prior art snap-on couplings has been undesirably high, as has their rate of failure.
Most wheel mounting sleeves typically require a wheel having a central wheel bore which is formed with shoulders which cooperate with the sleeves to lock or latch the sleeve to the wheel. The sleeve further is formed to latch the sleeve to a circumferentially extending notch provided on axles in wide spread use in the industry.
As set forth in my U.S. Pat. No. 6,637,835, an improved axle has been devised which has a stub extension beyond the conventional notch that seats in a recess in the wheel mounting sleeve to stabilize the end of the axle in the sleeve. Wheeled product manufacturers, however, would prefer having an axle which can be used with standard wheels having straight (cylindrical) bores, as well as with wheel mounting sleeves and wheels with cooperating, stepped wheel bores. Thus it would be highly advantageous to provide a universal axle structure that can be used with any one of push-on hat fasteners, washer and cotter pin assemblies, hub inserts and wheel mounting sleeves.
Typical prior art wheel-mounting assemblies can be seen in U.S. Pat. Nos. 486,023, 2,978,277, 3,907,370, 5,215,356, 5,222,786, 5,277,480, 5,603,555, 5,716,107, 5,902,018 and 6,099,083 and in published European Patent Application No. 0 180 307.
U.S. Pat. No. 486,023 to Bermel discloses an axle nut used to secure a wheel on a somewhat involved axle structure. Another wheel retaining axle nut is shown in U.S. Pat. No. 6,099,083 that also is designed for use with a cooperatively formed and unique notched axle.
In U.S. Pat. No. 2,978,277 to Gaudry a two-piece hub assembly is used to secure a wheel on an axle stub. The two hub halves are forced together to simultaneously capture the head of the axle and a dove-tailed cross section of the wheel. This approach is based, in part, upon mating frictional engagement of the hub halves, but under the shock loading and high vibration which refuse carts, cooler and toys typically experience, frictional securement of components can be unreliable. The need for multiple hub pieces and an axle with an enlarged head, also is not desirable and the end of the axle is not supported well against transverse loading.
The wheel-mounting assembly of U.S. Pat. No. 3,907,370 to Bard employs a mounting sleeve which is keyed to slide over the keyed end of a specially formed axle. The sleeve mates with spokes in a wheel recess and is held in place by a washer and cotter pin. An annular cap is placed over the cotter pin and washer. This approach requires axle keying, a plurality of parts, the use of tools to secure and release the cotter pin and cap, and a laterally unsupported axle end.
A multiple piece hub assembly is shown in U.S. Pat. No. 5,716,107 to Parker et al. In this wheel-mounting assembly a retainer member is used to lock the wheel assembly on a groove or annular notch at the end of the axle. The hub cover is snapped into the wheel and then the wheel snapped onto the axle. Such notched or grooved axles are in wide spread use in connection with trash carts, but this assembly again requires multiple pieces and, in this case, special tools and tedious manipulation are required in order to release the resilient retainer ring fingers from the inside of the wheel so that the wheel can be removed from the axle. A similar snap-on hub assembly is shown in U.S. Pat. No. 5,215,356. In both U.S. Pat. Nos. 5,716,107 and 5,215,356 the wheel securing device is not a sleeve which extends through the wheel bore.
Four patents which employ sleeve assemblies formed for mounting through the wheel in telescoped relation over the axle are shown in U.S. Pat. Nos. 5,222,786, 5,277,480, 5,603,555 and 5,902,018. The devices of U.S. Pat. Nos. 5,222,786 and 5,603,555 have sleeves with at least one snap-acting, axle-engaging shoulder thereon which releasably retains the sleeve on the axle and at least one wheel-engaging shoulder retaining the wheel on the sleeve. As will be seen, however, both of the wheel-mounting sleeve assemblies in these patents are relatively complex and employ a plurality of pieces in order to secure the wheel on the axle. As the wheel and axle size reduces, therefore, these assemblies become more difficult to employ.
In U.S. Pat. Nos. 5,277,480 and 5,902,018 separate retainer devices are used with sleeves, but the outer ends of the axles are essentially unsupported and hub covers must be employed for safety and/or aesthetic reasons.
Finally, in European publication No. 0 180 307 collets are provided on an inwardly cantilevered stub of the wheel to grip a notch formed in the axle. No through-the-wheel sleeve is employed in this assembly.
Accordingly, it is an object of the present invention to provide a wheel assembly and wheel mounting sleeve having a minimum number of parts which can be used to mount plastic wheels to notched or grooved metal axles.
A further object of the present invention is to provide a plastic wheel assembly for a trash cart, wagon, cooler or other wheeled product which is economical to manufacture, easy to mount to the axle, and is durable, stable and capable of withstanding substantial shock loads, side-to-side shifting and vibration during normal use.
Another object of the present invention is to provide a universal axle assembly which can be used with conventional straight bore wheels and conventional fastening devices, as well as with wheel mounting sleeves for wheels with cooperatively formed wheel bores.
Still another object of the present invention is to provide an axle wheel mounting sleeve and wheel in which the assembly formation of the wheel is easier to accomplish and proper seating of the axle and securement of the wheel thereon can be confirmed.
The wheel assembly axle and wheel mounting sleeve of the present invention have other objects and features of advantage which will become apparent from, and are set forth in more detail in, the accompanying Drawing and following Best Mode Of Carrying Out The Invention.